DE2631444A1 - METHOD AND APPARATUS FOR THE REMOVAL AND RECOVERY OF SULFUR DIOXIDE FROM EXHAUST GASES - Google Patents

Description

DIPL.-PHYS. WOLFGANG SEEGER I ** 4

PATENT ADVOCATE

THIERSCHSTR. D-8 MUNICH TEL. (O89) 22 51

Attorney's file: 4 Pat 10 > elegremm (Ceble Address):

Seegerpatent Munich Telex: 5 24487 patop d

Applicant; Lee Joseph Duvall
1855 Trevilian Way
Louisville, Kentucky 40205 / USA

"Process and device for the removal and recovery of sulfur dioxide from exhaust gases"

The invention relates to an effective method for extracting sulfur dioxide and water vapor from gaseous effluents emitted during the combustion of sulphurous materials, and a device for performing the method.

Lately there has been environmental pollution caused by the burning of sulphurous fuels occurs, given special attention, as essentially sulfur-free fuels are increasing become rare. While fuels containing sulfur, e.g. B. to generate electrical energy, burned there are copious amounts of sulfur dioxide, some of which are associated with water vapor are generated, and they have to be taken from the gas

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shaped outflow are removed "before this in the atmosphere is released. The present invention is, on the one hand, aimed at achieving these goals directed, and moreover it provides the possibility of a simple recovery of sulfur dioxide in commercially usable form.

There are numerous methods for removing harmful sulfur dioxide from exhaust gases, which at the combustion of sulphurous fuels emitted has been developed. To this end chemical scrubbers for gases, catalysts and fluidized beds have been developed; these devices however, almost all of them are very complex and expensive to manufacture, and moreover they do not allow in the removal of the sulfur dioxide components at the same time in easier Way the recovery of the final product as it is desired.

Other systems use extraction technology to remove sulfur dioxide from gaseous forms Discharge, the sulfur dioxide trapped in a catalytic or absorbent agent will. In this way, not only is the recovery of sulfur dioxide difficult, but in addition, the catalyst or the absorbent must after a relatively short time regenerated so that they can continue to be used.

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Other systems rely on the possibility of liquefying sulfur dioxide from its gaseous form Condition, see e.g. US-PS 1,810,312 and US-PS 1,939,694. However, these systems have significant Disadvantages on. A very significant disadvantage is, for example, that the efficiency of the Brenners can be reduced as a result of increasing and decreasing movement through the system.

There is therefore a need for, in an effective and at the same time simple manner, sulfur dioxide and remove associated water vapor from the gaseous effluents resulting from the Combustion of sulphurous materials emitted, and at the same time the recovery of the sulfur dioxide components in a commercially usable form.

The object of the invention is to efficiently remove sulfur dioxide and associated water vapor to remove gaseous effluents that are generated when burning fuels containing sulfur will. A further object of the invention is to provide the sulfur dioxide in a commercially usable form to regain. The aim is to create a simple and effective system that can be adapted to a large range of furnace or burner parameters can be adjusted without affecting their efficiency to affect.

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According to the invention it has been found that the above Task and the desired advantages by reducing air from the gaseous outflow, which in the combustion of sulfur-containing materials can be realized to reduce the sulfur dioxide and to liquefy water vapor components and to separate. When carrying out the invention, the chimney or exhaust gases are initially in one Heat exchanger is cooled and then compressed to a degree that liquefies sulfur dioxide and sufficient for condensation of water vapor, after which the recovery of the same by suitable Pressure isolator devices takes place, which allow constant, uninterrupted operation of the system. The liquid recovered in this way can be used commercially in various ways, e.g. as a bleaching agent for textile dyes etc., without the need for further extensive treatment would be. # The efficiency of the system and accordingly its usefulness will be through selective routing of the cooled exhaust gases in heat exchangers Relation to the hot chimney gases to support the cooling of the incoming gas reinforced. With the liquefaction device, a cooling chamber with a spray curtain is used, in which cold condensate is used for further Increasing the efficiency of the system is used.

Further advantages and features of the invention emerge from the following description of an exemplary embodiment with reference to the accompanying single figure emerged.

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There are several problems with the most efficient way to produce substantially sulfur-free exhaust gases. First of all, it was found that any water vapor content in the exhaust gases from combustion systems increases the extraction to the maximum, since water vapor can hold back fifty times its volume of sulfur dioxide even at room temperature. When burning superfluous fuels in conventional burners, about 10 % to 12 % water vapor is generated, compared to the total composition of the exhaust gases, whereby the removal of sulfur dioxide is reduced to a minimum. Therefore, the present invention is in part directed to an improvement by which the entrained water vapor component is similarly removed; this increases the overall efficiency of the process.

In a nutshell, one can say that the Kaminoder Exhaust gases, which are generated during the combustion of sulfur-containing fuel, initially be cooled in a heat exchanger. The cooled outflow, with the entrained sulfur dioxide component, is then compressed and fed to a first treatment chamber in which cold sulfur dioxide condensate is released into the exhaust gas stream is sprayed to remove some of the gaseous sulfur dioxide and water vapor. The outflowing medium, with the remaining sulfur dioxide and the remaining Water vapor is then fed into a second treatment chamber, in which the remaining sulfur dioxide and the remaining water vapor due to the combined effect of lowering the

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Temperature and the increase in pressure are removed. Part of the sulfur dioxide condensate can then be in the The first treatment chamber is used, while the remaining sulfur dioxide is fed to a collection chamber will; this is done via a pressure isolation device so that the entire system is isobaric and without decreasing and increasing movement works. The collected sulfur dioxide can then be used commercially.

The exhaust gases free of sulfur dioxide, which have been substantially cooled in the system, are released in a similar manner, with the pressure being controlled to produce a decreasing and increasing movement or a To prevent backflow movement through the burner, causing its uneven operation and a reduction its efficiency would fc cause. The cooled exhaust gases are then passed through a heat exchanger directed or otherwise brought into a heat-exchanging relationship with the fireplace gases, to reinforce the cooling capacity, while at the same time reducing the energy required from the outside is minimized.

In addition, the outflow can be guided by suitable means the environment of the system can be precisely controlled so that maximum efficiency is achieved will. If the system is operated in a hot environment, some of the cooled exhaust gases to cool the environment of the system. If, on the other hand, the system is in a relative cold environment, hot fireplace gases can be used to improve the environment of the system

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before they are introduced into the sulfur dioxide and water vapor removal system. Accordingly, when practicing the invention high economic efficiency can be achieved.

In the single figure is a system according to the invention shown, which helps to reduce air pollution by releasing sulfur dioxide into the Atmosphere as a result of combustion of sulphurous fuels is used. These fuels, usually Coal or oil, are burned in a furnace 10 so that they, for example, a steam for generating electrical Generate energy. The furnace has an inlet conduit 12 in a conventional manner and contains additionally a damper 14, which will be described in detail further below. the gaseous effluent resulting from the combustion of the fuel and considerable quantities of sulfur dioxide, which is at least partially assigned to the water vapor, is of the Burner 10 via an outlet line 16, and from there to the heat exchanger 18. Optionally, to increase the efficiency of the system, a device 15 for removing particles can be used. Such particle removers can Precipitators, bag filters or the like, which need not be described in more detail. Usually the gaseous outflow emanating from the burner 10 also reaches the heat exchanger 18 a temperature of about 150 degrees C. The temperature of the outflow can, however, depend from the efficiency of the furnace or from others

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Operating parameters, in the range between 100 degrees C. and 200 degrees C.

Taking into account the fact that the critical temperature of sulfur dioxide is around 158 degrees C it is necessary that the effluent is cooled to at least this temperature; preferably however, it should be cooled to a temperature in the range of about 55 degrees C to 65 degrees C. However, it is particularly preferred if the outflow is at a temperature in the range between minus 1 degree C and plus 5 degrees C is cooled. The required cooling is nLt with the help of a heat exchanger 18, which is of any known type, e.g. with counter-flowing liquid or air, can be. Preferably, a winged heat exchanger 18 is used, which which uses thermal conduction technology. These heat exchangers work almost isothermally and thus generate high recovery efficiency. Furthermore, there are no moving parts, which would require regular maintenance and, moreover, no external power source is necessary, whereby both the efficiency and the economy of the process can be increased. How to get in the Figure sees, the cooled gases can be cooled by the heat exchanger 18 to increase the efficiency to increase further. These cooled gases are then passed through a line 20, which is an auxiliary line 21 having a damper 26, out to an air compressor 22.

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22nd
The compressor / can be of known type and contain a rotor, a rotating screw, a centrifuge or the like. While the absolute manner in which the compressor operates is not of particular concern in this context, it is essential that the load capacity of the compressor 22 be greater than the required flow rate (CFM) of the furnace 10. If the-for the ma-

10

ximal efficiency of the burner / required flow rate has been calculated, ignoring the sulfur dioxide removal system a compressor 22 should be selected which has an excessive capacity of 10% to 15% compared to the required, optimal flow rate through the burner. These oversized capacity compensates for the volume loss caused by the sulfur dioxide removal system. In coordination with the compressor 22, the damper 26 can controllably air out of the Environment flow through the auxiliary line 21. In fact, the damper 26 functions as a compensator valve to compensate for the differences between the volume of the fireplace gases that use the burner leave, and the volume which is sucked in by the compressor 22, the admission the required flow velocity of air from the environment of the furnace 10 compensates.

To separate the sulfur dioxide components from the gaseous effluent, it is necessary to to compress the gases to a degree which corresponds to the thermodynamic pressure-temperature relationship the vapor-liquid equilibrium of sulfur

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corresponds to dioxide. This degree of compression is automatically determined by a first sensing of the temperature the gaseous outflow caused by the temperature sensor 32, which can be of any type and outputs electrical, mechanical or hydraulic output signals to a valve 42, which then is automatically controlled to produce the desired degree of compression in the system. A Gas stream that has been cooled to about 25 degrees C, for example, requires a degree of compression which leads to an absolute pressure of about 4 kg / cm, thus the liquefaction of the sulfur dioxide component is initiated. Due to such considerations as the rise in the temperature of the gas flow, which with the compression entering the compressor 22 (e.g., heat compression), it is desirable to provide an absolute pressure of at least about 5 to 6 kg / cm. It must also be taken into account be that the chemical interaction between the components of the flow has a degree of compression make necessary, which is above the theoretical degree of compression.

The compressed gases are sent from the compressor via a line 25 to a first cooling chamber 27 guided; this is a cooling chamber with a spray curtain, and it is for special use modified along with the sulfur dioxide removal system. The cooling chamber 27 has a number of spray heads 28 which produce spray columns 29. As detailed below

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as described, the recovered sulfur dioxide condensate is pumped to the cooling chamber 27, and this condensate forms the multitude of spray columns made of highly dispersed sulfur dioxide.

The compressed gases which flow out from the compressor have experienced an increase in temperature due to their compression. The cooling chamber 27 partially compensates for this increased temperature, since the spray columns consist of cold condensate with a temperature between approximately 1 ° C to 5 ° C. The action of this spray curtain causes an initial, partial removal of sulfur dioxide from the effluent, and at the same time it causes an initial separation of water vapor due to the tendency to condense on the cold condensate particles in the columns 29 and in connection with the increased pressure due to the action of the compressor 22. After sulfur dioxide and water vapor have been partially removed from it, the outflowing gas leaves the cooling chamber 27 via a line 30, which has a temperature sensor, and is led to a treatment chamber "5k .

The compressed gas flow which enters the treatment chamber 34 occurs, follows an approximately sinusoidal path around diverting or separating parts 36 which the sulfur dioxide component is liquefied due to the temperature decrease, which has been generated by the heat exchanger 18 and the increase in pressure in the air compressor 22

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is. The treatment or process chamber 34 is divided by a perforated plate 40 and has a lower one Collection chamber 38 on. The liquid sulfur dioxide, which has been removed from the gas stream, runs on the separating parts 36 down through the perforated plate 40 and collects in the chamber 38.

The temperature sensor 32 works in coordination with the Pressure sensor 33 and the one-way valve 42, together with the dampers 14 and 26 described above. It is essential that the burner 10 operate at a constant

speed

Flow works without increasing or decreasing flow, so that its efficiency assumes a maximum value. If changes to the burner are required, are both the pressure-temperature ratio, which is necessary for the effective separation of sulfur dioxide and water vapor is required as well as affecting the volume flow of the gas. When such changes occur supplies the temperature sensor 32 a suitable signal, which is an electrical, hydraulic or may be a mechanical signal and the one-way valve 42 controls so that a suitable change in the volume flow rate the outflow from the system is enabled, which directly affects the pressure in the System acts. In connection with this operation, the pressure sensor 33 signals the valve 42 in a similar way Way that the required pressure in the chamber 34 has been reached. Because of the dispersions and changes the operating flow rates, the dampers 14 and 26 are automatically adjustable so that a wide range of flow rates through the system is provided. In particular, the damper 14 is

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selectively adjustable so that a constant flow rate is generated by the burner 10, which is the most effective flow rate for that burner and this flow rate is over the entire range of the operating parameters of the Burner independently variable, regardless of the operating parameters of the attached removal system. Since the operating parameters of the removal system depend on the pressure-temperature requirements in it change, air is selectively admitted into the system through damper 26 for the most effective removal of Sulfur dioxide is achieved.

If, for example, the burner 10 has a flow rate of about 470 m / min Air required for the most effective 'operation,' becomes the whole / admitted this air through the damper 14. Because of the quality of the fuel used may change the volume of the fireplace gas slightly, however, this has little, if any, impact on these initial requirements. The compressor 22 draws air through the damper 14 while the damper 26 is adjusted accordingly, preferably automatically, so that this constant value of approximately 470 nr / min air through the burner 10 is ensured is. If the required pressure in the treatment chamber 34 varies depending on the temperature change, for example changes, the damper 26 is automatically opened or closed to appropriate operating conditions to ensure, but a constant current flow through the burner 10 is allowed. Accordingly the system is capable of efficiently and efficiently producing sulfur dioxide and water

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to generate steam from the gaseous effluent over an adjustable controllable range of about 4.7 m / min to about 4700 rar / min.

As noted above, it is highly desirable to remove water vapor because water vapor binds sulfur dioxide many times its volume. It has been found that for optimal removal of water vapor in the treatment chamber 34 a temperature of about 4 degrees C to 5 degrees C and a pressure of about 7 kg / cm should prevail, so that a dew point between about 4 degrees C and 5 degrees C. is produced. When operating in this range, exhaust gas is obtained that is about 99 % free of water vapor.

The liquid sulfur dioxide and the condensed water vapor, which are collected in the chamber 38, via a line 46 through a level-controlled valve 48 and passed via a line 50 to an insulation chamber 52, which guides the condensate to a Storage device 54 allows without influencing the system pressure in the treatment chamber 34.

When the level of liquid sulfur dioxide falls below a predetermined value, a float 56 causes the Opening of the level-controlled valve 58 so that condensate is let in from the treatment chamber 38 to the chamber 52 will. Simultaneously with the opening of the valve 48, a float 58 causes the level control valve 60 is closed. As the liquid level rises, the floats 56 and 58 cause the corresponding Valves 48 and 60 are closed and opened, respectively, so that the liquid from the isolation chamber

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can be routed to the memory. The fluid is thus removed from the system under essentially isobaric conditions.

The cold condensate that is in the isolation chamber Stored at a temperature between about 1 degree C to 5 degrees C can then be used as a source for the described Cooling columns 29 are used. As long as the system works long enough to produce significant amounts of To collect condensate, the cooling chamber 27 with the spray curtain is out of operation. As soon as. But once the The level of the condensate in the isolation chamber 52 has reached a constant value, a part of it can with A pump 64 can be brought to the spray nozzles 28 via a line 62. The spray columns 29 support the temperature decrease of the gaseous flow and at the same time cause an initial, partial Removal of sulfur dioxide and water vapor. The liquid that collects in the chamber 27, is returned via line 66 to the isolation chamber.

The removal of sulfur dioxide and water vapor from the gaseous effluent results in a cold residue from the release to the atmosphere. This cold residue passes through the under pressure control conditions One-way valve 42 and is selectively performed in the vicinity of a heat exchanger 18 or is otherwise placed in heat-exchanging relationship with the hot, incoming flow, eliminating the overall requirements to be reduced to the system. It is then delivered via line 45.

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In a similar way, the cold residue can be used alone or in coordination with hot fireplace gases, to influence or control the environment of the system. That is, through appropriate management of the hot and / or cold gas streams in a heat-exchanging relationship with the surroundings of the device can be applied to them a temperature range between about 10 degrees C and about 16 degrees C. This feature increases the efficiency of the process and the economy of the system increased. For example, the hot fireplace gases can be selectively directed through a conventional radiator in order to heat the environment in a suitable manner. Similarly, if so desired is, the cold exhaust gases from the line 43 are optionally diverted through the radiators of an air conditioning system.

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Claims (9)

263KU claims 1. A process for removal and recovery of sulfur 'dioxide contained in a gas stream which is emitted from the combustion of sulfur-containing materials in a burner _for which the effective operation of a predetermined flow rate of air has, characterized in that that the gas flow is cooled, that the gas stream is compressed, that the pressure of the gas flow is felt, that the temperature of the gas flow is sensed, that selective by a Stromungsdämpf ungseinrichtung a volume of air is admitted to the gas flow depending on its pressure-temperature conditions, to maintain the predetermined air velocity through the burner, thereby increasing and decreasing the Flow through it is essentially prevented, that the sulfur dioxide is liquefied in order to produce a residual flow essentially free of sulfur dioxide obtain, that the residual flow in a controlled manner to the atmosphere depending on the pressure and temperature of which is emitted, and that the gas stream is brought into contact with liquid sulfur dioxide condensate before liquefaction. 2. The method according to claim 1, characterized in that the residual flow is brought into a heat-exchanging relationship with the gas flow before it is released to the environment. 709808/0741 263UA4 3. The method according to claim 1 or 2, characterized in that the liquefied sulfur dioxide is collected and part of it is returned to the touch process stage. 4. The method according to any one of claims 1 to 3> thereby characterized in that the gas stream is cooled to a temperature between about 1 degree C and about 5 degrees C and to a pressure of at least 7000 g / cm (100 p.s.i.g.) is compressed. 5. The method according to any one of claims 1 to 4, characterized in that the environment in which the Process is carried out, is influenced in a controlled manner by optionally the residual flow and / or the Gas flow is brought into heat-exchanging relation with the environment, whereby the temperature of the Environment is maintained in a range between approximately 10 degrees C and 16 degrees C. 6. Device for removing and recovering sulfur dioxide contained in a gas stream that is emitted when sulfur-containing materials are burned in a burner, which has a predetermined flow rate of air for effective operation, characterized by a device for cooling the gas flow, by a device for compressing the gas flow, by means of a device for sensing the pressure of the gas flow, by means of a device for sensing the temperature of the gas flow, 709808/0741 " ¹⁹ ". 263HU by a flow damping device, which selectively a volume of air to the gas stream depending on its pressure-temperature condition allows to maintain the predetermined air velocity through the burner, whereby a Increase and decrease of the flow is essentially prevented by it, by a device for liquefying the sulfur dioxide to generate an essentially sulfur dioxide-free residual flow, by a device for the controlled release of the residual flow to the atmosphere as a function of their pressure and temperature conditions, and by a device which connects the gas stream with a concentrate of liquid sulfur dioxide brings. 7. Apparatus according to claim 6, characterized by a device for collecting the liquid sulfur dioxide and for returning a portion thereof to the touch device. 8. Apparatus according to claim 6, characterized by a device for the optional guidance of the residual flow in heat exchange relation with the gas flow. 9. Device according to one of claims 6 to 8, characterized by a device for optional guidance the residual flow and / or the gas flow in heat-exchanging relation with the environment of the device, whereby the temperature of the environment within a range of about 10 degrees C to 16 degrees C. is regulated. 709808/07 Blank page